218408646693 has 4 divisors (see below), whose sum is σ = 291211528928. Its totient is φ = 145605764460.

The previous prime is 218408646653. The next prime is 218408646719. The reversal of 218408646693 is 396646804812.

218408646693 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 218408646693 - 2³⁶ = 149689169957 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218408646653) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36401441113 + ... + 36401441118.

It is an arithmetic number, because the mean of its divisors is an integer number (72802882232).

Almost surely, 2^218408646693 is an apocalyptic number.

It is an amenable number.

218408646693 is a deficient number, since it is larger than the sum of its proper divisors (72802882235).

218408646693 is an equidigital number, since it uses as much as digits as its factorization.

218408646693 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72802882234.

The product of its (nonzero) digits is 11943936, while the sum is 57.

The spelling of 218408646693 in words is "two hundred eighteen billion, four hundred eight million, six hundred forty-six thousand, six hundred ninety-three".